When both surfaces of wafers are simultaneously polished by a polishing process, the wafers are held with carriers for use in a double-side polishing apparatus. Each carrier is formed so as to have a thickness thinner than that of the wafer and a holding hole to hold the wafer at a prescribed position between a upper turn table and a lower turn table of the double-side polishing apparatus. The wafer is inserted and held in the holding hole. The upper and lower surfaces of the wafer are interposed between polishing means such as polishing pads attached to opposing faces of the upper turn table and the lower turn table and polished while a polishing agent is supplied to polishing surfaces.
Mainstream carriers for use in this type of double-side polishing of wafers are made of metal such as titanium or stainless steel, or glass epoxy. In a metal carrier, an insert made of resin such as engineering plastic to protect the edge of a wafer from being damaged by the carrier is attached along an inner circumferential portion of its holding hole.
In this way, polishing with the carrier having the insert attached between the holding hole and the wafer allows the prevention of the damage to the wafer edge.
As disclosed in, e.g., Patent Document 1, a production method of fixing the insert to the carrier by means of engaging, sticking, injection molding, or other means is given as this type of method of producing a carrier for use in a double-side polishing apparatus.
Patent Document 2 discloses that after an insert is engaged, the thickness of the insert and the carrier is equalized by a polishing process so as to make their height equal.
There is also a producing method that involves engaging a groove formed on the inner circumference of a holding hole of a carrier body with a protrusion formed on the outer circumference of an insert (See Patent Document 3). This method makes an attempt to inhibit the insert from slipping out of position and falling off to prevent the wear of the insert and a sag on an outer circumference portion of a workpiece due to the wear during workpiece polishing processes.